Guardiola's side lost 4-0 in their Group C encounter against the Spanish giants at the Nou Camp
Guardiola's side lost 4-0 in their Group C encounter against the Spanish giants at the Nou Camp on October 19 - their fifth defeat in as many meetings with the Catalan club.
City goalkeeper Claudio Bravo was sent off in that match and Guardiola acknowledged the importance of keeping 11 players on the pitch against a side of Barcelona's class.
"We know we need to play almost perfectly," Guardiola, who guided Barcelona to two Champions League titles while manager from 2008-12 after starring for the club as a player, told a news conference on Monday.
"It's always difficult in the Champions League. Ten versus 11 against Barcelona is almost impossible. We have to improve that otherwise it is impossible to achieve the target.
"I have never thought we can't win a football match and I will never start to think that way, even though we lost 4-0. We'll give it a go. We know it is difficult and they are a difficult opponent.
"Maybe we are going to change the way we press, the build-up, many things. I would like to play in a good level. What passed in Barcelona, that is not the reason for what it is going to happen here.
"We have to be focused in 90 minutes knowing they are going to provoke our mistakes with the quality they have. In that moment we try to keep going and finish better than in Barcelona."
Barcelona top the group at the halfway point with three victories from their three matches, while City have four points after a draw against Celtic and victory over Borussia Moenchengladbach.
Guardiola said the group standings meant Tuesday's match was of greater significance for City than Barcelona.
"It is not a final for them. It is a final for us," the 45-year-old explained.
"There are just three games left. We dropped two points in Glasgow against Celtic and we need to recover those points.
"Every manager, every trainer has his plans. We know them, they know us. But football is unpredictable. Hopefully our quality in front can make a difference.
"In the first half we played well at Camp Nou but the two wide players for Barcelona are almost unstoppable. The only thing I can ask of our players is they play the way they know."
With Bravo suspended following his red card in the first fixture, Willy Caballero will start in goal for the match at the Etihad Stadium and Guardiola has every confidence in the 35-year-old goalkeeper.
"He has helped me very much from the first few games," Guardiola said.
"I like Willy on a personal level and as a goalkeeper he has played and given a lot of confidence. If he plays well, we're all be happy with him. If he doesn't, then we will support him. But I have no doubts about him."
City forward Nolito also said striker Sergio Aguero will be a key player against Barcelona and insisted his team-mates have the self-belief needed to beat the La Liga champions.
"I think he's one of the best strikers in the world," Nolito said. "And it's a pride to have him in the team and we hope he has one of those days where he scores lots of goals.
"Sincerely, we have to beat Barcelona one day. We have to win this one because of the situation we're in. We have to. Knowing how strong they are we will have to be at our best."